A projector is proposed that corrects distortion of an image using a pickup image (also referred to as trapezoidal distortion correction, trapezoid correction, keystone correction, etc.). For the projector to appropriately correct the distortion of the image, exposure during imaging needs to be appropriately set. For example, Japanese Patent Publication No. 2006-60447 describes that an image of a totally white pattern (an image that is entirely white), an image of a black and white checker pattern, and an image of a totally black pattern (an image that is entirely black) are picked up with fixed exposure to detect frames of the images and frames of a screen and an image of the totally black pattern is picked up with automatic exposure to complementarily detect the frames of the screen in the pickup image.
However, in Japanese Patent Publication No. 2006-60447, it is unclear with what kind of exposure the images are picked up when the images are picked up with the fixed exposure. For example, when exposure setting is too high, a white void occurs in a pickup image and, when exposure setting is too low, contrast of a pickup image falls and it is difficult to appropriately detect a boundary line or the like included in the pickup image.